Research On Trajectory Tracking Strategy Of Wheeled Mobile Platform Based On Vision

Visual servoing(also termed as “Vision-based control”)refers to using visual sensors to obtain image information,and then to control the movement of the mobile robot to reach the desired position/orientation or track a specific trajectory.This technology combines computer vision algorithms with robot motion control,which can give full play to the advantages of vision sensors,and then greatly improve the intelligence of mobile robot.Nowadays,some research achievements have been made in the field of track tracking of wheeled mobile platform based on vision.but the design and analysis of vision controller of mobile robot has become a challenging problem in the field of automatic control because of the limitation of complex non-integrity constraints.This dissertation focuses on the trajectory tracking strategy of wheel-based mobile platform based on vision,and provides some effective solutions for the mobile servo visual servo trajectory tracking system.The overall work of the dissertation is summarized as follows:(1)First of all,the visual servo principle of the mobile robot under incomplete constraint system is introduced,then the kinematics model and the imaging model of the pinhole camera are established,what's more,the visual servo method based on the homography matrix is introduced.Then,the hardware experimental platform of the mobile robot visual servo track tracking system is built,and the contents of the experimental program code are expounded.Finally,in the actual programming process,it was abstracted and encapsulated according to the idea of high cohesion and low coupling,which has good scalability.(2)In order to complete the mobile robot vision servo trajectory tracking task,the dissertation presents an effective wheeled mobile robot vision servo trajectory tracking strategy,which can accurately track the desired motion trajectory without introducing additional variables.Through the kinematics model analysis of the robot,the estimation and decomposition of the homography matrix,the proportional translation vector and rotation angle required to define the systematic error are obtained.Then,the trajectory tracking control law of the mobile robot was designed by adaptive method.The stability of the proposed control strategy was proved by Lyapunov theory and Barbara's theorem.Finally,a classical visual servo method is selected for comparison.Simulation and contrast experiments prove the effectiveness of the method.(3)In order to complete the task of tracking the visual servo trajectory of mobile robot under the condition of speed saturation constraint,the dissertation presents a visual servo control strategy.By introducing a series of continuous and bounded functions that are used as saturated input control,the kinematics model of the mobile robot and the homography matrix are decomposed,and the trajectory tracking error is designed based on the translation vector and rotation angle obtained by the decomposition.The control strategy of the velocity saturation input constraint is designed based on the adaptive method.According to Lyapunov's theory and Lasalle's Invariance Principle proves the effectiveness of the control strategy,and simulation and experimental results verify the feasibility of the method.